CVE-2026-68148 (GCVE-0-2026-68148)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:59 – Updated: 2026-08-19 16:30
VLAI
Title
fscrypt: Add missing superblock check in find_or_insert_direct_key()
Summary
In the Linux kernel, the following vulnerability has been resolved: fscrypt: Add missing superblock check in find_or_insert_direct_key() The legacy 'fscrypt_direct_keys' table caches master keys that are used by v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY. It's just a global table for all filesystems (since the keys can be provided by the legacy process-subscribed keyrings mechanism, which makes it difficult to reuse super_block::s_master_keys). The entries in it ('struct fscrypt_direct_key') do contain a super_block pointer, though, for passing to fscrypt_destroy_inline_crypt_key() when the last inode that references the key is evicted. However, when finding the fscrypt_direct_key for an inode, we weren't actually comparing the super_block pointer. As a result, inodes with different super_blocks could point to the same fscrypt_direct_key. That could extend the lifetime of a fscrypt_direct_key beyond the super_block it points to, causing a use-after-free later. Fix this by creating distinct fscrypt_direct_key structs for distinct super_block structs. Note that this problem doesn't exist in the v2 policy equivalent ("per-mode keys"), since the data structures there are per super_block.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 22e9947a4b2ba255888541bd0111cf00b9b16586 , < 965b5bc8cf5031225e057979ce660fec2bd5fbfc (git)
Affected: 22e9947a4b2ba255888541bd0111cf00b9b16586 , < 330249609b70778094a7a36f5b6bcfa6362121d4 (git)
Affected: 22e9947a4b2ba255888541bd0111cf00b9b16586 , < deff41898a5ae3a47db5fa1896a494aa95efda5d (git)
Affected: 22e9947a4b2ba255888541bd0111cf00b9b16586 , < 95376fe9c145be35566991df99c53134943d992f (git)
Affected: 22e9947a4b2ba255888541bd0111cf00b9b16586 , < 466f187b501a5ac8e1ea2ccf3ccd5c46108d8830 (git)
Affected: 22e9947a4b2ba255888541bd0111cf00b9b16586 , < b5fa40226e71c17847b9ff2816c6ca4133d0d994 (git)
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Linux Linux Affected: 6.1
Unaffected: 0 , < 6.1 (semver)
Unaffected: 6.1.183 , ≤ 6.1.* (semver)
Unaffected: 6.6.148 , ≤ 6.6.* (semver)
Unaffected: 6.12.101 , ≤ 6.12.* (semver)
Unaffected: 6.18.42 , ≤ 6.18.* (semver)
Unaffected: 7.1.6 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfscrypt: Add missing superblock check in find_or_insert_direct_key()\n\nThe legacy \u0027fscrypt_direct_keys\u0027 table caches master keys that are used\nby v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY.\nIt\u0027s just a global table for all filesystems (since the keys can be\nprovided by the legacy process-subscribed keyrings mechanism, which\nmakes it difficult to reuse super_block::s_master_keys).\n\nThe entries in it (\u0027struct fscrypt_direct_key\u0027) do contain a super_block\npointer, though, for passing to fscrypt_destroy_inline_crypt_key() when\nthe last inode that references the key is evicted.\n\nHowever, when finding the fscrypt_direct_key for an inode, we weren\u0027t\nactually comparing the super_block pointer.  As a result, inodes with\ndifferent super_blocks could point to the same fscrypt_direct_key.  That\ncould extend the lifetime of a fscrypt_direct_key beyond the\nsuper_block it points to, causing a use-after-free later.\n\nFix this by creating distinct fscrypt_direct_key structs for distinct\nsuper_block structs.\n\nNote that this problem doesn\u0027t exist in the v2 policy equivalent\n(\"per-mode keys\"), since the data structures there are per super_block."
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              "value": "AV:L - The flaw is reached only through local syscalls (mount/umount, FS_IOC_SET_ENCRYPTION_POLICY, and file I/O that calls fscrypt_get_encryption_info -\u003e find_or_insert_direct_key); fscrypt is not invoked from network-facing kernel services.\nAC:L - An attacker who can mount two encrypted filesystems with the same v1 DIRECT_KEY master key, share the global cache entry, then unmount the first superblock can deterministically trigger eviction-time cleanup on a freed super_block without races or victim-dependent timing.\nPR:L - Exploitation requires mounting/unmounting filesystems and setting v1 DIRECT_KEY policies (CAP_SYS_ADMIN in a user/mount namespace) or supplying keys via process keyrings; per kernel guidance, CAP_SYS_ADMIN obtainable in user namespaces maps to PR:L.\nUI:N - No separate victim action is required; the attacker sets v1 DIRECT_KEY policies, accesses encrypted inodes on two mounts, and controls unmount/eviction to hit the vulnerable refcount and cleanup path.\nS:U - The use-after-free corrupts kernel heap memory and enables local privilege escalation within the same kernel; it does not cross VM, hypervisor, or IOMMU security boundaries.\nC:H - Extending a fscrypt_direct_key past its super_block lifetime causes cleanup to dereference a freed super_block in fscrypt_destroy_inline_crypt_key(), a use-after-free that can leak kernel memory and support arbitrary-read exploitation primitives.\nI:H - Use-after-free during inline-crypto key destruction on a dangling super_block pointer can be leveraged for heap corruption and arbitrary kernel writes, enabling local privilege escalation rather than only a controlled crash.\nA:H - Evicting the last inode holding the mismatched fscrypt_direct_key dereferences a freed super_block during key teardown, which can cause kernel oops/panic and complete local denial of service on encrypted mobile/embedded and server systems using inline encryption."
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68148",
    "datePublished": "2026-08-10T11:59:13.413Z",
    "dateReserved": "2026-07-30T09:28:09.371Z",
    "dateUpdated": "2026-08-19T16:30:13.417Z",
    "state": "PUBLISHED"
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As a result, inodes with\\ndifferent super_blocks could point to the same fscrypt_direct_key.  That\\ncould extend the lifetime of a fscrypt_direct_key beyond the\\nsuper_block it points to, causing a use-after-free later.\\n\\nFix this by creating distinct fscrypt_direct_key structs for distinct\\nsuper_block structs.\\n\\nNote that this problem doesn\u0027t exist in the v2 policy equivalent\\n(\\\"per-mode keys\\\"), since the data structures there are per super_block.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/crypto/keysetup_v1.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"22e9947a4b2ba255888541bd0111cf00b9b16586\",\"lessThan\":\"965b5bc8cf5031225e057979ce660fec2bd5fbfc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"22e9947a4b2ba255888541bd0111cf00b9b16586\",\"lessThan\":\"330249609b70778094a7a36f5b6bcfa6362121d4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"22e9947a4b2ba255888541bd0111cf00b9b16586\",\"lessThan\":\"deff41898a5ae3a47db5fa1896a494aa95efda5d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"22e9947a4b2ba255888541bd0111cf00b9b16586\",\"lessThan\":\"95376fe9c145be35566991df99c53134943d992f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"22e9947a4b2ba255888541bd0111cf00b9b16586\",\"lessThan\":\"466f187b501a5ac8e1ea2ccf3ccd5c46108d8830\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"22e9947a4b2ba255888541bd0111cf00b9b16586\",\"lessThan\":\"b5fa40226e71c17847b9ff2816c6ca4133d0d994\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/crypto/keysetup_v1.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.1\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.1\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.183\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.148\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.101\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.42\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.6\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/330249609b70778094a7a36f5b6bcfa6362121d4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/466f187b501a5ac8e1ea2ccf3ccd5c46108d8830\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/95376fe9c145be35566991df99c53134943d992f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/965b5bc8cf5031225e057979ce660fec2bd5fbfc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b5fa40226e71c17847b9ff2816c6ca4133d0d994\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/deff41898a5ae3a47db5fa1896a494aa95efda5d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-13T23:18:36+00:00",
      "cve": "CVE-2026-68148",
      "id": "CVE-2026-68148",
      "initial_release_date": "2026-08-10T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "92",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: fscrypt: Add missing superblock check in find_or_insert_direct_key()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68148.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-18T16:56:06Z",
      "cve": "CVE-2026-68148",
      "id": "CVE-2026-68148",
      "initial_release_date": "2026-08-18T16:56:06Z",
      "product_status:known_affected": "217",
      "product_status:known_not_affected": "79",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-68148",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68148.json",
      "version": "2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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